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Abstract:

The present invention relates to an amine composition comprising linear
triethylene-tetramine and one or more amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine as well as a method of production for said
composition.
The present invention also relates to the use of linear
triethylenetetramine or an amine composition according to the invention
as amine curing agents.
The present invention also relates to amine curing agent compositions
comprising linear triethylenetetramine as well as to curable compositions
comprising linear triethylenetetramine and to a method for producing said
curable compositions.
Additionally, the present invention relates to a cured epoxy resin
comprising linear triethylenetetramine, especially a reinforced
composite, and a method for producing said cured epoxy resins.
Furthermore, the present invention relates to reactive polyamide resins
obtainable from linear triethylenediamine and dimer fatty acids.

Claims:

1-15. (canceled)

16. An amine composition comprising from 85 to 98% by weight of
triethylenetetramine of formula I ##STR00008## and 15% or less by
weight of one or more amine compounds selected from the group consisting
of tertiary amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine,
based on the sum of the weight of TETA of formula I and the weight of the
amine compounds selected from the group consisting of tertiary amines
derived from the condensation of ethylenediamine and methyl-substituted
compounds derived from linear triethylenetetramine.

17. A method for the production of the amine composition according to
claim 16 by distillation of a reaction effluent obtained from the
reaction of ethylene oxide with ammonia or by distillation of a reaction
effluent obtained from the catalytic hydrogenation of
ethylenediaminediacetonitrile.

18. An amine curing agent comprising the triethylenetetramine of formula
I having a purity of 98% by weight or more and/or the amine composition
according to claim 16.

19. An amine curing agent composition comprising an amine curing agent
selected from the group consisting of the amine composition according to
claim 16 and triethylenetetramine of formula I having a purity of 98% by
weight or more, and one or more other amine curing agents.

20. The amine curing agent composition according to claim 19, wherein the
content of the amine curing agent is selected from the group consisting
of the amine composition according to claim 16 and triethylenetetramine
of formula I having a purity of 98% by weight or more is 25% by weight or
more, based on the weight of the amine curing agent composition.

21. The amine curing agent composition according to claim 20, wherein the
content of the amine curing agent selected from the group consisting of
the amine composition according to claim 16 and triethylenetetramine of
formula I having a purity of 98% by weight or more is in the range of 25
to 99% by weight or more, based on the weight of the amine curing agent
composition.

22. A curable composition comprising one or more epoxy resins and the
amine curing agent composition according to claim 19; or at least one
amine curing agent selected from the group consisting of the amine
composition according to claim 16 and triethylenetetramine of formula I
having a purity of 98% by weight or more, wherein the weight ratio of
triethylenetetramine of formula I to amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine is 85:15 or more.

23. A method for the production of the curable composition according to
claim 22 by mixing the amine curing agent composition according to claim
19 or at least one amine curing agent selected from the group consisting
of the amine composition according to claim 16 and triethylenetetramine
of formula I having a purity of 98% by weight or more, with at least one
epoxy resin.

24. A method for the production of a cured epoxy resin by transferring
the curable compositions according to claim 22 to a mold or applying said
curable compositions to a surface.

25. The method for the production of a cured epoxy resin according to
claim 24, wherein the curable composition is applied to a reinforcing
agent and cured in the presence of the reinforcing agent to form
reinforced composites.

26. Cured epoxy resins obtainable by a method according to claim 24.

27. Epoxy resins comprising an amine composition comprising more than 85%
by weight of triethylenetetramine of formula I or the amine curing agent
composition according to claim 19 for the manufacture of epoxy resins.

28. A reactive polyamide resin obtained from the reaction of the amine
composition according to claim 16 and/or triethylenetetramine of formula
I having a purity of 98% by weight or more with dimer fatty acids.

29. A method of producing reactive polyamide resins by heating the amine
composition according to claim 16 and/or triethylenetetramine of formula
I having a purity of 98% by weight or more with dimer fatty acids and
removing the condensation product water by distillation.

30. Reactive polyamide resins produced from the amine composition
according to claim 16 and/or triethylenetetramine of formula I having a
purity of 98% by weight or more.

Description:

[0001] The present invention relates to an amine composition comprising
linear triethylene-tetramine and one or more amine compounds selected
from the group consisting of tertiary amines derived from the
condensation of ethylenediamine and methyl-substituted compounds derived
from linear triethylenetetramine as well as a method of production for
said composition.

[0002] The present invention also relates to the use of linear
triethylenetetramine or an amine composition according to the invention
as amine curing agents.

[0003] The present invention also relates to amine curing agent
compositions comprising linear triethylenetetramine as well as to curable
compositions comprising linear triethylenetetramine and to a method for
producing said curable compositions.

[0006] Curable compositions on the basis of amine curing agents and epoxy
resins are used in the industry on a large scale to produce cured epoxy
resins. Common applications include flooring, civil engineering, marine
and industrial coatings, adhesives, tooling, composites, castings,
composite lamination and encapsulations.

[0007] Epoxy resins are an important class of polymeric materials,
characterized by the presence of more than one epoxy-ring. The epoxy
resins are converted into cured epoxy resins, which are solid, infusible
and insoluble 3-dimensional networks, with the help of curing agents,
which can undergo chemical reactions with the epoxy rings of the epoxy
resin.

[0008] Commonly amines are used as functional curing agents. These amines
can be either primary or secondary amines. A primary amine group can
react with two epoxy groups while a secondary amine can react only with
one epoxy group. Usually, primary amine groups react much faster than
secondary amine groups. Tertiary amines, which have no active hydrogen,
will not react with the epoxy groups at all, but will generally act as a
catalyst to accelerate the epoxy reaction.

[0009] The reactivity of amines depends also on their chemical nature.
Aliphatic amines are generally more reactive than cycloaliphatic amines,
which are in turn more reactive than aromatic amines. Aliphatic amines
are therefore suitable for curing epoxy-resins at room temperature
whereas aromatic amines generally require higher curing temperatures.

[0010] Aromatic amines are usually employed in applications requiring high
temperature stability because they lead to final materials having a high
glass transition temperature (Tg). Also aromatic amines result in
materials having a good resistance to chemicals. The light stability of
aromatic curing agents is on the other hand insufficient for some
applications. Since many aromatic amines are solid at room temperatures
and due to their lower reactivity, they usually require elevated
temperature cures. In addition, the viscosity of the epoxy systems is
higher than that of aliphatic or cycloaliphatic amines. Cycloaliphatic
amines can result in materials having a Tg approaching those of
aromatic amines.

[0011] An aliphatic amine composition which is widely used as curing agent
for epoxy resins is commercially available triethylenetetramine (TETA).
"Commercially available TETA" has been commonly produced by the reaction
of ethylene dichloride with aqueous ammonia, which produces the
hydrochloride salts of ethylenediamine and higher homologues. The
reaction is usually carried out in the liquid phase without a catalyst.
Treatment with caustic soda liberates the free amines. The process yields
various derivetives of ethylenediamine (EDA), such as piperazine,
diethylenetriamine, triethylenetetramine, tetraethylenepentamine,
pentaethylenehexamine and aminoethylpiperazine, which are separated by
distillation. However, distillation does not yield pure linear TETA, but
a mixture of linear TETA with cyclic and branched compounds. The
composition of "commercially available TETA" is specified, e.g. in the
Screening Information Data Set of the Organization for Economic
Co-Operation and Development (OECD SIDS) for "triethylenetetramine"
(published by UNEP Publications, July 1998, available under
www.inchem.org/documents/sids/sids/112-24-3.pdf).

[0012] According to the above mentioned reference, the content of linear
TETA of formula (I)

[0013] Minor amounts of further side products, such as
aminoethylethanolamine (AEEA), N-(2-aminoethyl)piperazine (AEPIP),
hydroxyethylpyrrolidon (HEP) and tetraethylenepentamine (TEPA) may be
also present.

[0014] DAEPIP (II), PEEDA (III) and TAEA (IV) are amine compounds
comprising a tertiary amine group having the following formulas:

##STR00002##

[0015] The use of the designation "triethylene tetramine" or "TETA" for
the above mentioned mixture gives rise to some confusion, because the
designation "triethylene tetramine" or "TETA" commonly used and known in
the epoxy industry does not refer to the linear compound of formula I but
to the commercially available mixture. In general, the linear compound of
formula I is not commercially available in a purity higher than 70%.
Therefore references made to "TETA" or "triethylene tetramine" in the
literature relating to epoxy resins generally refer to the commercially
available mixture and not to the linear compound of formula I.

[0016] "Pure TETA" or "purified TETA" having a purity higher than 98% was
reported in US-A-2006/0041170 and in the above mentioned OECD SIDS.
US-A-2006/0041170 describes the use of essentially pure TETA in
pharmaceuticals. However these publications do not refer to the use of
"pure" or "purified TETA" in epoxy applications.

[0017] In the context of the present invention the term "linear TETA"
designates the compound of formula I. The term "commercially available
TETA" refers to the industrially and commercially available product
having a content of about 60 to 70% by weight of linear TETA as described
above. Further, the terms "pure TETA" or "purified TETA" depict
compositions comprising linear TETA having a content of linear TETA of
98% by weight or more.

[0018] As mentioned above, the use of "commercially available TETA" as a
curing agent in epoxy resins is well established due to its high
availability and is low price. "Commercially available TETA" shows good
curing properties. These curing properties may be attributed to the
presence of the tertiary amines which act as a catalyst in the reaction
between primary and secondary amines with epoxides. A good curing
behavior decreases the time in which form parts can be demolded leading
to shorter production cycles. In addition, the use of "commercially
available TETA" results in epoxy systems having a low brittleness. The
setback of using "commercially available TETA" is the fact that due to
the high content of tertiary amines, which can be present in an excess of
30% by weight and which do not participate in the curing reaction, only
low network densities are achieved which results in epoxy resins having a
low glass temperature of typically less than 120° C. Higher glass
transition temperatures are often desirable because it broadens the
temperature range in which form parts made of epoxy resin can be applied.
For "commercially available TETA", higher glass transition temperatures
can generally not be achieved without sacrificing other properties, such
as the curing properties characterized by the gel time, setting time,
time of hardening or curing time or the handling properties characterized
by the latency time or the pot life or the mechanical properties, e.g.
the brittleness.

[0019] The curing time, gel time, setting time or time of hardening
usually all refer to the time required for a resin to effectively
solidify at the molding temperature. In the context of the present
invention the term curing time will be used to denote this property. A
reduced curing time enables a shorter demolding time or a quicker release
of form parts from their molds which allows for shorter production
cycles.

[0020] The latency time or the pot life usually both refer to the length
of time that a resin system retains a viscosity low enough to be used in
processing. In the context of the present invention the term pot life
will be used to denote this property. A long pot life enables the filling
of complicated forms to make complex form parts and ensures a high level
of process stability.

[0021] For example, the addition of additional linear amines, such as
ethylenediamine (EDA) would result in an increase of the glass transition
temperature but would also lead to an increase in the curing time due to
a dilution of tertiary amine components. Furthermore, the characteristic
mechanical properties of "commercially available TETA" would be
detrimentally affected by the substitution with other linear amines. In
addition, lower amines, such as EDA, have a lower boiling point and
therefore contribute to an undesired increase of volatile organic
compounds (VOC).

[0022] The addition of cycloaliphatic or aromatic amines would also
increase the glass transition temperature. But cycloaliphatic and
aromatic amines are generally less readily available and significantly
more costly than aliphatic amines. Therefore, the use of cycloaliphatic
and aromatic amines would significantly decrease the economic viability
of epoxy systems making them unattractive for large scale applications.
Aromatic and cycloaliphatic amines generally have a higher viscosity
which effects flowability and processing of the epoxy mixture. Aromatic
or cycloaliphatic amines would also lead to an increase of the curing
time because of their reduced reactivity. In addition, the use of
aromatic amines decreases the light stability and leads to a
discoloration of the resin.

[0023] The object of the present invention is to provide an aliphatic
amine curing agent leading to cured epoxy resins having a higher glass
transition temperature without an increase in curing time and a decrease
of the pot life in order to attain excellent mechanical properties of
resulting cured epoxy resins and superior processing properties of the
curable compositions.

[0024] The problem of the present invention is solved by an amine
composition comprising from 85 to 98% by weight of triethylenetetramine
of formula I

##STR00003##

and 15% by weight or less of one or more amine compounds selected from
the group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine, based on the sum of the weight of TETA of formula I
and the weight of the amine compounds selected from the group consisting
of tertiary amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine.

[0025] The composition of the present invention comprises linear TETA of
formula I, which is referred to as "linear TETA" as defined above.

[0026] The composition of the present invention also comprises one or more
amine compounds selected from the group consisting of tertiary amines
derived from the condensation of ethylenediamine and methyl-substituted
compounds derived from linear triethylenetetramine.

[0027] In a preferred embodiment of the present invention the amine
compound selected from the group consisting of tertiary amines derived
from the condensation of ethylenediamine and methyl-substituted compounds
derived from linear triethylenetetramine is a tertiary amine derived from
the condensation of ethylenediamine.

[0028] Within the frame of the present invention "tertiary amines derived
from the condensation of ethylenediamine" are termed "TADE". The term
"TADE" designates cyclic and branched derivatives of ethylenediamine
(EDA) which may be considered to be built by the condensation of two or
more EDA molecules and which have at least one tertiary amine group per
molecule. The tertiary amines derived from the condensation of
ethylenediamine usually have a degree of condensation of 2 or more,
preferably 2 to 10, more preferably 2 to 6 and especially 2 to 4. Within
the context of the present invention the degree of condensation refers to
the number of EDA-molecules which condense to obtain the respective TADE.

[0029] TADE can be subdivided into cyclic tertiary amines which are
derivatives of EDA ("cyclic TADE") and branched tertiary amines which are
derivatives of EDA ("branched TADE").

[0030] Cyclic TADE can be characterized by general formula (V)

##STR00004##

wherein R1 is H and R2 is CH2CH2X or wherein R1
and R2 are both CH2CH2X; wherein X═NR32; and
wherein Rican be both or individually be H or CH2CH2X; and
wherein the degree of condensation is preferably 2 to 10, more preferably
2 to 6 and more preferably 2 to 4.

[0031] Cyclic TADE include but are not limited to
bis(aminoethyl)piperazine (DAEPIP) (degree of condensation=4) of formula
II and (piperazinoethyl)ethylenediamine (PEEDA) (degree of
condensation=4) of formula III.

[0032] Branched TADE can be characterized by general formula (VI)

N(CH2CH2X)3 (VI)

wherein X can be both or individually NR32; and wherein R3
can be both or individually be H or CH2CH2X; and wherein the
degree of condensation is preferably 2 to 10, more preferably 2 to 6 and
more preferably 2 to 4.

[0034] In another preferred embodiment of the present invention the amine
compound selected from the group consisting of tertiary amines derived
from the condensation of ethylenediamine and methyl-substituted compounds
derived from linear triethylene-tetramine is a methyl-substituted
compound derived from linear triethylenetetramine.

[0035] In the context of the present invention, methyl-substituted
compounds derived from linear triethylenetetramine are understood to mean
any derivative of linear triethylene-tetramine (linear TETA) in which
one, two or more of the hydrogen atoms bonded to the four amino functions
of the unsubstituted linear TETA are substituted by the corresponding
number of methyl groups (CH3--). In the following, these compounds
will be subsumed under the term "Me-TETA".

[0036] Me-TETA can be characterized by formula (VII)

##STR00005##

wherein R is either H or CH3; with the proviso that at least one
substituent R is CH3.

[0037] Me-TETAs according to the present invention are shown by way of
example in scheme 1 below as compounds (2) to (13).

##STR00006##

[0038] The methyl-substituted compounds derived from linear
triethylenetetramine comprise Me-TETA with one (mono-Me-TETA; compounds 2
and 3), two (bis-Me-TETA; compounds 4 to 8) and three methyl substituents
(tris-Me-TETA; compounds 9 to 13). In addition, the term Me-TETA also
comprises Me-TETAs in which four, five or all six hydrogen atoms of the
unsubstituted TETA are substituted by methyl groups (not shown in Scheme
1).

[0039] The methyl-substituted compounds derived from linear
triethylenetetramine are preferably a mono-Me-TETA. More particularly,
the methyl-substituted TETA compound is selected from
N-2-aminoethyl-N'-(2-N''-methylaminoethyl)-1,2-ethanediamine
(sec-Me-TETA) and
N-2-aminoethyl-N-methyl-N'-2-aminoethyl-1,2-ethanediamine (tert-Me-TETA).
sec-Me-TETA and tert-Me-TETA are depicted in scheme 1 as compounds 2 and
3 respectively.

[0040] The amine composition of the present invention comprises 85 to 98%
by weight of linear TETA of formula I, based on the sum of the weight of
TETA of formula I and the weight of the amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine, preferably 90 to 98% by weight, more preferably 92
to 98% by weight and especially 93 to 98% by weight.

[0041] The composition of the present invention may preferably also
comprise 90 to 97% and more preferably 92 to 96% by weight of linear TETA
of formula I, based on the sum of the weight of TETA of formula I and the
weight of the amine compounds selected from the group consisting of
tertiary amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine.

[0042] The composition of the present invention comprises 15% by weight or
less of amine compounds selected from the group consisting of tertiary
amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine,
preferably 10% by weight or less, more preferably 8% by weight or less
and especially 7% by weight or less, based on the sum of the weight of
TETA of formula I and the weight of the amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine. The composition of the present invention may
preferably also comprise 0.01 to 10%, 0.1 to 8% or 1 to 5% by weight of
amine compounds selected from the group consisting of tertiary amines
de-rived from the condensation of ethylenediamine and methyl-substituted
compounds derived from linear triethylenetetramine, based on the sum of
the weight of TETA of formula I and the weight of the amine compounds
selected from the group consisting of tertiary amines derived from the
condensation of ethylenediamine and methyl-substituted compounds derived
from linear triethylenetetramine.

[0043] Preferably, the amine composition contains less than 5% by weight
of bis(aminoethyl)-piperazine (DAEPIP), based on the sum of the weight of
TETA of formula I and the weight of the amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine.

[0044] More preferably, it contains less than 2% by weight of DAEPIP, and
particularly preferably it contains less than 1% by weight of DAEPIP,
based on the sum of the weight of TETA of formula I and the weight of the
amine compounds selected from the group consisting of tertiary amines
derived from the condensation of ethylenediamine and methyl-substituted
compounds derived from linear triethylenetetramine.

[0045] Preferably, the amine curing agent composition contains less than
5% by weight (piperazinoethyl)ethylenediamine (PEEDA), based on the total
weight of the amine curing agent composition. More preferably, it
contains less than 2% by weight of PEEDA, and particularly preferably it
contains less than 1% by weight of PEEDA. Preferably, the amine curing
agent composition contains less than 3% by weight of
tris(aminoethyl)amine (TAEA), based on the sum of the weight of TETA of
formula I and the weight of the amine compounds selected from the group
consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine.

[0046] Particularly preferably, the amine curing agent composition
contains less than 2% by weight of piperazine derivatives, such as DAEPIP
and PEEDA. In particular, the overall content of piperazine derivatives
is less than 1% by weight.

[0047] The amount of water and other organic side products is preferably
less than 5% by weight, more preferably less than 2% by weight and most
preferably less than 1% by weight, based on the sum of the weight of TETA
of formula I and the weight of the amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine.

[0048] The content of linear TETA of formula I and the second amine
component selected from the group consisting of tertiary amines which are
derivatives of ethylenediamine (TADE) and methyl-substituted TETA
compounds (Me-TETA) can be determined using gas chromatography.

[0049] Amine compositions according to the present invention may be
obtained by distillation of a reaction effluent obtained from the
reaction of ethylene oxide with ammonia or by distillation of a reaction
effluent obtained from catalytic hydrogenation of
ethylenediaminediacetonitrile (EDDN).

[0050] The amine composition of the present invention can be
advantageously obtained either as a top or as a side stream in the
distillation of said reaction effluents.

[0051] In a preferred embodiment, amine compositions according to the
present invention can be obtained by distillation of a reaction effluent
obtained from the reaction of ethylene oxide with ammonia.

[0052] An overview of the reaction of ethylene oxide with ammonia is
presented in the SRI-Report "CEH Product Review Ethylenamines"; SRI
International, 2003, p. 7-8 and the PERP Report No. 138, "Alkyl-Amines",
SRI International 03/1981, pages 81 to 99 and page 117.

[0053] The reaction effluent of the reaction between ethylene oxide and
ammonia usually contains ammonia, water, EDA, DETA, TETA and higher
boiling amines (e.g. diethanolamine (DEOA), tetraethylenepentamin (TEPA),
N-[1-(2-piperazine-1-yl-ethyl)]-ethane-1,2-diamine (C8-PIP)), piperazine
and piperazine derivatives, especially AEPIP, as well as
aminoethylethanolamine (AEEA). The reactor effluent is usually liberated
from low boiling components such as ammonia and water, e.g. in the manner
described in the above mentioned PERP Report.

[0054] The remaining products are usually introduced into another
distillation column, in which a lower boiling mixture of EDA and
piperazine is taken overhead. The column is usually operated at 1 bar.

[0055] The high boiling fraction is usually fed into a distillation
column, which may be operated at 400 mbar, in which unreacted
monoethanolamine (MEOA) is removed at the head of the column.

[0056] The bottom product, which contains DETA, TETA, AEPIP and AEEA and
higher boiling compounds is usually then fed to another column, which may
be operated at 100 to 150 mbar, and in which DETA is taken overhead. The
bottom product comprises TETA, AEPIP and AEEA as well as other higher
boiling amines.

[0057] This mixture is generally fed into another distillation column
where AEPIP is removed at the top of the distillation column, which is
usually operated at a pressure of 1 to 50 mbar. Higher boiling amines,
such as AEEA and TETA, are removed at the bottom. In a subsequent stage,
the bottom products comprising AEEA, TETA and higher boiling amines are
fed into another distillation column, which may also be operated at a
pressure of 1 to 50 mbar. AEEA is removed at the top of the column
whereas TETA and higher boiling amines are obtained as a bottom product.

[0058] In a final distillation stage, the TETA composition according to
the present invention is usually separated from higher boiling amines at
a pressure of 1 to 50 mbar. The TETA composition according to the present
invention can either be removed at the top of the column or as a side
stream. If small amounts of AEEA are still present, it may be
advantageous to remove the TETA composition as a side stream.

[0059] The detailed operating conditions of the respective distillation
column may be routinely calculated and adapted by a person skilled in the
arts taking into account the separating efficiency of the respective
distillation column using the known vapour pressures and vapour pressure
equilibria.

[0060] TETA compositions according to the present invention may be
obtained by distillation of commercially available diethylenetriamine
residues, which comprise AEEA, TETA and higher boiling amines, and which
are obtained from the reaction of ethylene oxide with ammonia and
subsequent distillation. Such diethylenetriamine residues are
commercially available, e.g. as AMIX 1000, BASF SE. Amine compositions
according to the present invention may be obtained by feeding
commercially available diethylenetriamine residues into distillation
column, which may also be operated at a pressure of 1 to 50 mbar. AEEA is
removed at the top of the column whereas TETA and higher boiling amines
are obtained as a bottom product. In a second distillation stage, the
TETA composition according to the present invention is usually separated
from higher boiling amines at a pressure of 1 to 50 mbar. The TETA
composition according to the present invention can either be removed at
the top of the column or as a side stream. If small amounts of AEEA are
still present, it may be advantageous to remove the TETA composition as a
side stream. The detailed operating conditions of the respective
distillation columns may vary slightly depending on the exact composition
of the diethylenetriamine residues and may be routinely calculated and
adapted by a person skilled in the arts taking into account the
separating efficiency of the respective distillation column using the
known vapour pressures and vapour pressure equilibria.

[0061] The amine composition obtained as a side stream usually has a
content of linear TETA of 85 to 98% by weight, preferably 90% to 98% by
weight and more preferably 93 to 98% by weight, based on the sum of the
weight of TETA of formula I and the weight of the amine compounds
selected from the group consisting of tertiary amines derived from the
condensation of ethylenediamine and methyl-substituted compounds derived
from linear triethylenetetramine.

[0062] The amine composition obtained as a side stream may also comprise
90 to 97% and more preferably 92 to 96% by weight of linear TETA of
formula I, based on the sum of the weight of TETA of formula I and the
weight of the amine compounds selected from the group consisting of
tertiary amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine.

[0063] In addition, the amine composition comprises 15% by weight or less,
more preferably 10% by weight or less and more preferably 8% by weight or
less of tertiary amines de-rived from the condensation of ethylenediamine
(TADE), based on the sum of the weight of TETA of formula I and the
weight of the amine compounds selected from the group consisting of
tertiary amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine.

[0064] The amine composition may preferably also comprise 0.01 to 10%, 0.1
to 8% or 1 to 5% by weight of tertiary amines derived from the
condensation of ethylenediamine, based on the sum of the weight of TETA
of formula I and the weight of the amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylenetetramine.

[0065] In another preferred embodiment, the amine composition according to
the present invention may also be obtained by rectification or
distillation of a reaction effluent obtained from catalytic hydrogenation
of ethylenediaminediacetonitrile (EDDN). EDDN in turn is obtainable by
reacting EDA with formaldehyde and hydrogen cyanide (HCN). The reaction
of EDA with formaldehyde and hydrogen cyanide can be per-formed in
different variants, for example by forming the formaldehyde cyanohydrin
(EACH) intermediate, by first reacting formaldehyde and hydrogen cyanide
in the absence of EDA. Reaction mixtures obtained from the hydrogenation
of EDDN are disclosed in the examples of WO-A-2008104553. These reaction
mixtures generally contain linear TETA, aminoethylpiperazine (AEPIP) and
C4-components, such as diethylenetriamine (DETA) and piperazine (PIP) as
well solvent, e.g. THF. The content of TETA in the hydrogenation effluent
according to the examples of WO-A-2008104553 is generally between 30 and
less than 85% by weight.

[0066] In a preferred embodiment, the amine composition according to the
present invention is obtained by freeing a reaction effluent obtained
according to the examples of WO-A-2008104553 from solvents. Solvents, in
particularly THF, can generally be re-moved by expanding the effluent to
normal pressure and then feeding the effluent to a distillation column
operated at normal pressure. THF is generally removed at the head of the
column. If additional solvents are used, further distillation stages may
be necessary.

[0067] The amine fraction obtained as the bottom product and which is
essentially free of sol-vents is generally fed to another distillation
stage.

[0068] In this distillation stage, which is preferably operated at 100 to
500 mbar, lower boiling components such as lower boiling side products
and DETA are removed at the column head.

[0069] A mixture comprising AEPIP and TETA as well as other higher boiling
amines is usually fed into another distillation column, which is
preferably operated at 1 to 50 mbar, where AEPIP is usually removed at
the top whereas TETA and higher boiling amines are removed at the bottom.

[0070] The bottom product from the previous distillation stage is usually
further distilled in a subsequent distillation column also operated in a
range of 1 to 50 mbar. A TETA composition according to the present
invention is usually removed at the top of the column or as a side
stream. Higher boiling amines are generally removed at the bottom of the
column.

[0071] The detailed operating conditions of the respective distillation
columns may be routinely calculated and adapted by a person skilled in
the arts taking into account the separating efficiency of the respective
distillation column using the known vapour pressures and vapour pressure
equilibria.

[0072] The amine composition obtained as a side stream generally has a
content of linear TETA of 85 to 98% by weight, preferably 90% to 98% by
weight and more preferably 93 to 98% by weight, based on the sum of the
weight of TETA of formula I and the weight of the amine compounds
selected from the group consisting of tertiary amines derived from the
condensation of ethylenediamine and methyl-substituted compounds derived
from linear triethylenetetramine.

[0073] The amine composition obtained as a side stream may also comprise
90 to 97% and more preferably 92 to 96% by weight of linear TETA of
formula I, based on the sum of the weight of TETA of formula I and the
weight of the amine compounds selected from the group consisting of
tertiary amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine.

[0074] In addition, the amine composition generally comprises 15% or less
by weight of methyl-substituted TETA compounds (Me-TETA), more preferably
10% by weight or less of methyl-substituted TETA compounds (Me-TETA) and
most preferably 8% by weight or less of methyl-substituted TETA compounds
(Me-TETA).

[0075] The amine composition may also comprise 0.01 to 10%, 0.1 to 8% or 1
to 5% by weight of methyl-substituted compounds derived from linear
triethylenetetramine, based on the sum of the weight of TETA of formula I
and the weight of the amine compounds selected from the group consisting
of tertiary amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine.

[0076] Unexpectedly it has been found that cured epoxy resins in which the
amine compositions of the present invention are used as amine curing
agents have a significantly higher glass transition temperature compared
to epoxy resins obtained from "commercially available TETA". In addition
the curing time decreases while concurrently the pot life of the curable
compositions comprising the amine composition according to the invention
is lengthened. Furthermore, the characteristic mechanical properties
attributed to "commercially available TETA" are maintained.

[0077] It has however also been discovered that the improvement of the
properties in epoxy systems is not limited to the use of the amine
composition of the present invention as amine curing agent but may also
be extended to the use of "pure" or "purified TETA" having a content of
linear TETA according to formula I of more than 98% by weight as an amine
curing agent for epoxy applications. Such "pure" or "purified TETA" may
be obtained according to a process described in US-A-2006/0041170. "Pure"
or "purified TETA" may also be obtained by further purification of an
amine composition according to the present invention or in analogy to the
described methods for production of the amine composition of the present
invention by adaptation of the distillation conditions and sequences
described above for the production of the amine compositions according to
the invention, e.g. by increasing the number of theoretical plated in the
final distillation stage.

[0078] Therefore, the present invention also relates to the use of
triethylenetetramine of formula I having a purity of 98% by weight or
more and/or an amine composition according to the present invention as an
amine curing agent.

[0079] In principle, the amine composition according to the present
invention can be used as the sole amine curing agent or it can optionally
be mixed other amine curing agents, such as the one described below, to
form an amine curing agent composition. Likewise, "pure" or "purified
TETA" having a content of linear TETA according to formula I of more than
98% by weight can be used as the sole amine curing agent or it can
optionally be mixed other amine curing agents, such as the one described
below, to form an amine curing agent composition.

[0080] The advantageous effects achieved by using TETA according to
formula I of more than 98% by weight ("pure" or "purified TETA") or the
amine composition according to the present invention having a high
content of linear TETA of formula I as compared to the prior art
"commercially available TETA" will be less pronounced when diluted with
other curing agents, but will still be present.

[0081] Therefore, the present invention also relates to an amine curing
agent composition comprising an amine curing agent selected from the
group consisting of an amine composition according to claim 1 and
triethylenetetramine of formula I having a purity of 98% by weight or
more, and one or more other amine curing agents.

[0082] Other amine curing agents are amine compounds having at least one
or more, preferably two or more reactive amine hydrogen atoms in the
molecule capable of reaction with an epoxy functionality.

[0083] Preferably, the other amine curing agents which may be used in
combination with the amine curing agent selected from the group
consisting of triethylenetetramine of formula I having a purity of 98% by
weight or more and an amine composition according to the present
invention are:

heterocyclic amines, such as piperazine, N-aminoethylpiperazine;
cycloaliphatic amines, such as isophoron diamine, 1,2-(1,3;
1,4)-diaminocyclohexane, cyclohexylaminopropylamine (CHAPA),
tricyclododecan diamine (TCD); aromatic amines, such as the isomeric
phenylenediamines, such as o-phenylene-diamine, m-phenylenediamine,
p-phenylenediamine, the isomeric tolylenediamines, such as
2,4-diaminotoluene and/or 2,6 diaminotoluene, the isomeric
diaminonaphthalenes, such as 1,5-diaminonaphthalene,
bis(4-aminophenyl)methane (MDA), the isomeric xylenediamines, such
meta-xylenediamine (MXDA), bis(4-amino-3-methyl-phenyl)methane and
bis(4-amino-3,5-dimethylphenyl)-methane; substituted aliphatic amines
such as ethylene diamine, propylene diamine, hexamethylenediamine, 2,2,4
(2,4,4)--trimethylhexamethylene diamine, 2-methylpenta-methylene diamine;
ether amines such as 1,7-diamino-4-oxaheptane,
1,10-diamino-4,7-dioxydecane, 1,14-diamino-4,7,10-trioxatetradecane,
1,20-diamino-4,17-dioxyeicosan and in particular
1,12-diamino-4,9-dioxadodecane; ether diamines based on propoxylated
diols, trials and Polyols; polyalkylene polyamines, such as dipropylene
triamine, tripropylene tetramine; as well as high molecular amines or
addition or condensation products containing free amine hydrogen, in
particular Mannich bases.

[0085] In an preferred embodiment, the content of amine curing agent
selected from the group consisting of the amine composition according to
the present invention and triethylene-tetramine of formula I having a
purity of 98% by weight or more being present in the amine curing agent
composition according to the present invention is 25% by weight or more,
preferably 50% by weight or more, more preferably 75% by weight and more
and especially 90% by weight or more, based on the weight of the amine
curing agent corn-position.

[0086] Within the context of the present invention, the weight of the
amine curing agent composition is the sum of the weights of the amine
curing agents selected from the group consisting of an amine composition
according to the present invention and triethylene-tetramine of formula I
having a purity of 98% by weight or more and the other amine curing
agents, as defined above, which are used in the production of epoxy
resins.

[0087] In another preferred embodiment, the content of amine curing agent
selected from the group consisting of the amine composition according to
the present invention and triethylenetetramine of formula I having a
purity of 98% by weight or more being pre-sent in the amine curing agent
composition according to the present invention is from 25% to 99% by
weight, preferably from 50% to 95% by weight and more preferably from 75%
to 90% by weight, based on the weight of the amine curing agent
composition.

[0088] The amine composition according to the present invention or
triethylenetetramine of formula I having a purity of 98% by weight or
more or the amine curing agent compositions according to the present
invention can be mixed with epoxy resins to yield curable compositions.

[0089] Therefore, the present invention also relates to

curable composition comprising one or more epoxy resins and an amine
curing agent composition according to claims 4 to 6 or at least one amine
curing agent selected from the group consisting of an amine composition
according to claim 1 and triethylenetetramine of formula I having a
purity of 98% by weight or more, wherein the weight ratio of
triethylenetetramine of formula I to amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and methyl-substituted compounds derived from linear
triethylene-tetramine is 85:15 or more.

[0090] In a preferred embodiment, the curable compositions according to
the present invention comprise triethylenetetramine of formula I having a
purity of 98% by weight or more or the amine curing agent compositions
according to the present invention as the sole amine curing agent.

[0091] In a further preferred embodiment, the curable compositions
according to the pre-sent invention comprise the amine curing agent
compositions according to the present invention.

[0092] In addition to an amine curing agents and amine curing agent
compositions according to the present invention, the curable composition
also comprises one or more epoxy resins.

[0093] Epoxy resins are an important class of polymeric materials,
characterized by the presence of more than one epoxy-ring.

[0095] Commercially important epoxy resins are in particularly prepared by
the coupling reaction of compounds containing at least two active
hydrogen atoms with epichlorohydrin followed by dehydrohalogenation.
Compounds which contain at least two active hydrogen atoms include
polyphenolic compounds, mono and diamines, amino phenols, heterocyclic
imides and amides, aliphatic diols and polyols, and dimeric fatty acids.

[0096] Epoxy resins derived from epichlorohydrin are termed glycidyl-based
resins. Alternatively, epoxy resins based on epoxidized aliphatic or
cycloaliphatic dienes are produced by direct epoxidation of olefins by
peracids.

[0097] Epoxy resins also comprise reaction products of epichlorohydrin and
bisphenol A. These products are generally termed DGEBA (Diglycidyl ether
of bisphenol A). DGEBA where the degree of polymerization, n, is very low
(n≈0.2) is typically referred to as liquid epoxy resin (LER)
whereas high molecular weight (MW) epoxy resins based on DGEBA
characterized by a repeat unit containing a secondary hydroxyl group with
degrees of polymerization, i.e., n values ranging from 2 to about 35 are
generally de-noted as solid epoxy resins (SER).

##STR00007##

[0098] Epoxy resins also comprise so called epoxy novolac resins. The
multifunctionality of these resins provides higher cross-linking density,
leading to improved thermal and chemical resistance properties over
bisphenol A epoxides. Epoxy novolacs are multi-functional epoxides based
on phenolic formaldehyde novolacs. Both epoxy phenol novolac resins (EPN)
and epoxy cresol novolac resins (ECN) have attained commercial
importance. The former is made by epoxidation of the phenol-formaldehyde
condensates (novolacs) obtained from acid-catalyzed condensation of
phenol and formaldehyde.

[0099] The epoxy compounds which can be used for the curable compositions
and the cured epoxy resins derived therefrom are those resins described
above or mentioned in the cited literature, in particular commercial
products having more than one epoxy group per molecule on average, which
are derived from monovalent and/or multivalent and/or multinuclear
phenols, in particular bisphenols as well as novolacs, such as
bisphenol-A and bisphenol-F-diglycidylether.

[0104] The weight ratio of epoxy resins and the amine curing agent
compositions as well as additives and adjuvants may be varied to achieve
and refine the desired application properties of the final cured epoxy
and can be routinely determined by a person skilled in the art, e.g. the
amine curing agent may be contained in the composition in such an amount
that a molar ratio of epoxy groups of the epoxy resin to active hydrogen
atoms of the amine curing agent ranges from 0.7 to 1.1, preferably from
0.8 to 1.0.

[0105] Irrespective of whether the curable composition according to the
present invention comprises an amine curing agent composition according
to claims 4 to 6 or at least one amine curing agent selected from the
group consisting of an amine composition according to claim 1 and
triethylenetetramine of formula I having a purity of 98% by weight or
more, the curable compositions according to the present invention are
characterized in that the weight ratio of linear triethylenetetramine of
formula I to amine compounds selected from the group consisting of
tertiary amines derived from the condensation of ethylenediamine and
methyl-substituted compounds derived from linear triethylenetetramine is
85:15 or more, preferably 92:8 or more and more preferably 93:7 or more.
The weight ratio of linear triethylenetetramine of formula I to amine
compounds selected from the group consisting of tertiary amines derived
from the condensation of ethylenediamine and a methyl-substituted
compound derived from linear triethylenetetramine is also preferably from
85:15 to 99:1, more preferably from 90:10 to 98:2 and especially from
92:8 to 97:3.

[0106] In a preferred embodiment, the weight ratio of linear
triethylenetetramine of formula I to amine compounds selected from the
group consisting of tertiary amines derived from the condensation of
ethylenediamine and a methyl-substituted compound derived from linear
triethylenetetramine, is 98:2 or more. Such a curable composition may be
obtained by using "purified TETA" as the sole amine curing agent or by
mixing "purified TETA" and other amine curing agents.

[0107] The present invention also relates to a

method for the production of a curable composition according to claim 7
by mixing an amine curing agent composition according to claims 4 to 6 or
at least one amine curing agent selected from the group consisting of an
amine composition according to claim 1 and triethylenetetramine of
formula I having a purity of 98% by weight or more, with at least one
epoxy resin.

[0108] The process of mixing amine curing agents with one or more epoxy
resins is well known to a person skilled in the arts. Generally mixing is
effected by a mixing apparatus. The mixing apparatus can be of any type
that can produce a highly homogeneous mixture of the epoxy resin and
amine curing agent composition (and any optional components that are also
mixed in at this time). Mechanical mixers and stirrers of various types
may be used, Two preferred types of mixers are static mixers and
impingement mixers. Mixing can be conducted batch-wise, semi-continuously
or in a continuous fashion.

[0109] The epoxy resin and amine curing agent are generally separately
heated to above room temperature prior to mixing them together, so that a
curable composition is formed immediately upon mixing them. The epoxy
resin and amine curing agent may each be heated to a temperature of
25° C., preferably 50° C., more preferably 80° C.,
or higher prior to mixing.

[0110] Other additives, such as the ones mentioned above, may be mixed
with the amine curing agent or the epoxy resins prior to mixing the amine
curing agent with the epoxy resin. It is also possible to mix other
additives with the curable composition at the same time the amine curing
agent and the epoxy resin are mixed, or afterwards. After mixing, the
thus obtained curable composition is typically transferred to a suitable
mold (structural applications) or applied to a surface (coating
applications), e.g. by spraying the curable composition on a surface, to
obtain a cured epoxy resin.

[0111] Accordingly, the present invention further relates to a method of
producing a cured ep-oxy resin by transferring the curable compositions
according to the present invention to a mold or applying said curable
compositions to a surface.

[0112] Appropriate processing technologies are known to a person skilled
in the art and can be found e.g. in B. Ellis, "Chemistry and Technology
of Epoxy Resins", Kluwer Academic Publishers (February 1993),

[0113] Generally, the cured epoxy resins are obtained by allowing the
curable composition to set after mixing and transfer to a mold or after
application to a surface. During setting, the amine curing agents undergo
a reaction with the epoxy resins present in the cur-able composition.

[0114] In a preferable embodiment of the invention, mixing and transfer of
the curable composition is performed in one step, e.g. by reaction
injection molding. The epoxy resin and amine curing agent composition
(and optionally other components which are mixed in at this time) are
pumped under pressure into a mixing head where they are rapidly mixed
together. Operating pressures in high pressure machines may typically
range from 7 to 14 MPa, although operation at lower pressures is also
possible. The resulting curable composition is then preferably passed
through a static mixing device to provide further additional mixing, and
then transferred into the mold cavity.

[0115] In other embodiments, the curable composition is prepared by mixing
as described before, and then applied to a surface, in particular by
spraying the curable composition into a mold.

[0116] The mold is typically a metal mold, but it may be ceramic or a
polymer composite, pro-vided that the mold is capable of withstanding the
pressure and temperature conditions of the molding process. The mold
usually contains one or more inlets through which the reaction mixture is
introduced. The mold may contain vents to allow gases to escape as the
reaction mixture is injected. The mold is typically held in a press or
other apparatus which allows it to be opened and closed, and which can
apply pressure on the mold to keep it closed during the filling and
curing operations. The mold or press is provided with means by which heat
can be provided.

[0117] In a preferred embodiment of the present invention, the curable
composition is applied to a reinforcing agent and cured in the presence
of the reinforcing agent to form rein-forced composites.

[0118] Reinforcement agents may be, for example, blended with the epoxy
resin or the amine curing agent (or both), prior to mixing to obtain the
curable compositions. Alternatively, the reinforcing agents may be added
to the curable compostions at the same time as the epoxy resin and the
amine curing agent are mixed, or afterward but prior to introducing the
curable composition into the mold or applying the curable composition to
a surface, e.g. by spraying the curable composition into a mold.

[0122] Non fibrous reinforcing agents may also include conductive
materials, such as aluminum and copper, and carbon black, carbon
nanotubes, carbon fibers, graphite and the like.

[0123] The reinforcement agent can take any of several forms, such as a
fiber preform, continuous fiber rovings, cut fibers or chopped fibers.

[0124] Preferably the reinforcement agent is in form of a fiber preform,
i.e., a web or mat of fibers. The fiber preform can be made up of
continuous filament mats, in which the continuous filaments are woven,
entangled or adhered together to form a preform that approximates the
size and shape of the finished composite article (or portion thereof that
requires reinforcement). Alternatively, shorter fibers can be formed into
a preform through entanglement or adhesive methods. Mats of continuous or
shorter fibers can be stacked and pressed together to form preforms of
various thicknesses, if required. Fiber preforms are typically placed
into the mold prior to introducing the curable composition. The curable
composition can be introduced into a closed mold that contains the
preform, by injecting the curable composition into the mold, where the
curable composition penetrates between the fibers in the preform and then
cures to form a cured epoxy resin. Reaction injection molding and/or
resin transfer molding equipment is suitable in such cases.
Alternatively, the preform can be deposited into an open mold, and the
curable composition can be sprayed onto the preform and into the mold.
After the mold is filled in this manner, the mold is closed and the
curable composition is cured. In either approach, the mold and the
preform are preferably heated prior to contacting them with the curable
composition.

[0125] Short fibers can be used instead or in addition to a fiber preform.
Short fibers (up to about 20 cm in length, preferably up to 5 cm in
length, more preferably up to about 2 cm in length can be blended with
the curable composition and injected into the mold together with the
curable composition. Such short fibers may be, for example, blended with
the epoxy resin or the amine curing agent (or both), prior to mixing to
obtain the curable compositions. Alternatively, the short fibers may be
added into the curable compostions at the same time as the epoxy resin
and the amine curing agent are mixed, or afterward but prior to
introducing the curable composition into the mold. Short fibers can be
sprayed into a mold. In such cases, the curable composition can also be
sprayed into the mold, at the same time or after the short fibers are
sprayed in. When the fibers and the curable composition are sprayed
simultaneously, they can be mixed together prior to spraying.
Alternatively, the fibers and the curable composition can be sprayed into
the mold separately but simultaneously.

[0126] Various processes for the production of reinforced composites,
which are well-known by a person skilled in the arts, may be used such as
RTM, VARTM, RFI and SCRIMP. In these processes, a reinforcement agent in
form of woven or matted fiber preform is inserted into a mold cavity. The
mold is closed, and the resin is injected into the mold. The resin
hardens in the mold to form a composite, and is then demolded.

[0127] Reinforced composites may also be produced by pultrusion processes.

[0128] Pultrusion processes use continuous fibers that are oriented
parallel to each other, in the direction of extrusion. Pultrusion
processes are operated in a manner analogous to molding processes, the
main difference being that the hot reaction mixture is delivered into a
resin bath rather than into a mold. The resin bath is a reservoir filled
with the cur-able composition, through which the continuous fibers are
pulled. Once the fibers are wetted with the hot reaction mixture, they
are pulled through one or more dies, in which the fibers are consolidated
and formed into the desired cross-sectional shape.

[0129] It has been found that the amine curing agent compositions of the
present invention comprising a high content of linear TETA lead to cured
epoxy resins having a higher glass transition temperature Tg as
compared to commercially available prior art TETA mixtures containing
linear TETA, DAEPIP, PEEDA and TAEA. The higher Tg broadens the
temperature range in which cured epoxy resins can be applied. Mechanical
proper-ties of the epoxy resins severely decline as soon as Tg is
exceeded.

[0130] In addition, curable compositions according to the present
invention may be cured at higher temperatures, in particular according to
a process according to US-A-2008/0197526, which enables the fabrication
of reinforced composites, especially for automotive and aerospace
components.

[0131] The increase in Tg is not accompanied by an increase in curing
time of the curable compositions as would have been expected due to due
to the reduction of the content of catalytically active tertiary amines
in comparison to "commercially available TETA". It has been found that
using amine curing agent compositions according the present invention
significantly reduces the curing time as compared to prior art
"commercially available TETA". The reduced curing time leads to shorter
cycle times, which is in general advantageous in the production of form
parts, such as carbon fiber reinforced composites (CFK) small parts in
the automotive industry where a high throughput is desired.

[0132] The increase in Tg is also not accompanied by a deterioration
of the pot life and therefore the use amine curing agent compositions
used in the curable compositions according to the present invention give
rise to excellent processing properties and a high process stability. The
increase of Tg does not detrimentally effect the mechanical
properties characteristic for prior art "commercially available TETA".

[0133] The amine curing agents used in the process of the present
invention for the production of curable compositions and cured resins are
particularly suited for applications in the field of automotive
components and parts, wind turbines, filament wound pipe, printed
circuits, aircraft/aerospace, ordnance, sports/recreation, fiber
composites, construction and adhesives.

[0135] Cured epoxy resins based on curable compositions comprising LERs
based on DGEBA are widely used in the coatings industry. The longer
backbones generally give more distance between cross-links when
cross-linked through the terminal epoxy groups, resulting in improved
flexibility and toughness. Furthermore, the resins can also be cured
through the multiple hydroxyl groups along the backbones using
cross-linkers such as phenol--formaldehyde resoles or isocyanates to
create different network structures and performance.

[0136] Cured epoxy resins based on curable compositions containing Novalac
resins usually have a higher cross-linking density, leading to improved
thermal and chemical resistance properties over bisphenol A epoxides.
They are therefore often used in high temperature applications such as
aerospace composites. Filament wound pipe and storage tanks, liners for
pumps and other chemical process equipment, corrosion resistant coatings
are other typical applications, which take advantage of the high chemical
resistance.

[0137] The amine composition of the present invention and/or "pure" or
"purified" TETA may also advantageously be used for the production of
reactive polyamide resins.

[0138] Therefore the present invention also refers to reactive polyamide
resin, obtainable from the reaction of an amine composition according to
claim I and/or triethylenetetramine of formula I having a purity of 98%
by weight or more with dimer fatty acids.

[0139] Reactive polyamides are lower-molecular-weight (1,000-2,000 g/mol)
products from the condensation of dimer fatty acid and one of the higher
ethyleneamines (diethylenetriamine, triethylenetetramine and others).
Reactive polyamides are used almost exclusively as curing agents in
two-component epoxy systems for industrial and marine maintenance
coatings, thermosetting adhesive systems, electronics encapsulation and
flooring grouts and trowel coatings. Their amine groups provide reactive
sites for cross-linking interactions with epoxy resin molecules.

[0140] Reactive polyamides are usually produced in a batch condensation
process. The reactants (dimer fatty acid and the amine compositions
according the present invention and/or "pure" or "purified" TETA) are
generally heated to 150-250° C. By-product water is usually
removed by vacuum distillation. The resulting polyamide is then removed
and converted to forms suitable for shipping.

[0141] Dimer fatty acids are most frequently obtained by the
polymerization of monocarboxylic acids containing ethyleneic
unsaturation. The monocarboxylic unsaturated acids generally contain from
about 16 to 26 carbon atoms and include, for example, oleic acid,
linoleic acid, eleostearic acid and similar singly or doubly unsaturated
acids. To obtain the preferred dimer acids 2 mols of the unsaturated
monocarboxylic acid are reacted, i.e., dimerized. Oleic acid, linoleic
acid and linolenic acid are generally used as unsaturated fatty acids.
The dimer acids, obtained in this manner, can subsequently be
hydrogenated.

[0142] Reactive polyamide resins obtained from the reaction of dimer fatty
acids and amine compositions according to the invention and/or "pure" or
"purified" TETA have a higher functionality compared to reactive
polyamide resins obtained from conventional TETA. The higher
functionality results in an increase of mechanical properties of the
resulting systems. Surprisingly it has been found that reactive polyamide
resins obtained from the reaction of dimer fatty acids and amine
compositions according to the invention and/or "pure" or "purified" TETA
have a higher content of imidazoline rings formed as a side product in
the reaction of the carboxylic acid group of the dimer fatty acid and
TETA of formula I. It is believed that imidazoline ring formation is
concurrent with the improvement of intercoat adhesion

[0146] This effluent was fed into the mid section of a distillation column
operated at 50 mbar and a top temperature of 154° C. AEEA and the
lower boiling amine fraction were re-moved at the top of the column and a
mixture of higher boiling amines and TETA was removed at the bottom of
the column. The bottom product of the first reaction column was fed into
the middle of a second distillation column operated at 30 mbar and a
temperature at the column top of 164° C. An amine composition was
removed as a top stream.

[0148] 100 g of Epilox® A18-00 epoxy resin (Epilox® A 18-00 is a
low viscosity and solventless bisphenol A epoxy resin produced by
LEUNA-Harze GmbH) were mixed with 14 g of an amine curing agent
composition consisting of the amine composition obtained in example 1.

[0149] The following studies were conducted on the resin mixture.

a) Determination of the onset temperature of the crosslinking reaction by
DSC (differential scanning calorimetry)

[0150] The onset temperature of the crosslinking reaction was 62°
C.

b) Pot life measurement 100 g of the resin mixture were placed in a
cardboard beaker at room temperature. A data logger is used to measure
the temperature of the sample as a function of time.

[0151] The latency of the resin mixture with pure linear TETA as hardener
was longer than that of the comparative example (see below) at the
beginning, but the mixture then cured to completion very rapidly.

c) Determination of the gel point by rheological study

[0152] The activity of resin systems was determined by monitoring the
progress of reaction using a rheometer. This involves plotting a variable
known as the storage modulus against a variable known as the loss
modulus. The point at which the two curves inter-sect is referred to as
the gel point. The corresponding reaction time is known as the gel time,
and constitutes a measure of the reactivity of the epoxy resin system.

[0153] A gel time of 8.3 minutes was found.

d) DSC is used to determine the glass transition temperature of the cured
epoxy resin. Cured epoxy resins possess good mechanical properties when
the service temperature is <the glass transition temperature. Above
the glass transition temperature there is a dramatic deterioration in the
mechanical properties of the epoxy resins.

[0154] The glass transition temperature was found to be 136° C.

Example 3

Comparative Example

[0155] 100 g of Epilox® A18-00 epoxy resin were mixed with 14 g of
"commercially available TETA" from Akzo, containing about 69% by weight
linear triethylenetetramine, about 6% by weight TAEA, about 15% by weight
DAEPIP, and about 10% by weight PEEDA.

[0156] The studies as described above were conducted on the resin mixture.

a) The onset temperature of the crosslinking reaction was 58° C.
b) The latency time of the comparative resin mixture was shorter than
that of the resin mixture of the inventive example. c) The gel time was
found to be 9.3 minutes. d) The glass transition temperature Tg was found
to be 115° C.

[0157] The glass transition temperature of the epoxy resin cured with the
amine curing agent composition comprising the amine composition according
to the present invention was approximately 21° C. higher than that
of the comparative resin. Accordingly the resin of the inventive example
can be used at significantly higher temperatures. The higher onset
temperature of the crosslinking reaction and the longer latency time of
the inventively cured epoxy resin are technically advantageous from a
processing standpoint and offer additional safety, since the
autocatalytic curing reaction does not begin until later.

[0158] The cure time (gel time) of the epoxy resin is shortened by
approximately 15% over the comparative example through the use of pure
linear TETA. This is accompanied by a shortening in the cycle times, with
beneficial effects for investment costs in the case, for example, of
high-volume manufacture of moldings, such as of small carbon fibre
reinforced plastic (CRP) components in the automotive sector.

Example 4

[0159] 4.7 g of Raney-Cobalt and 40 g of tetrahydrofurane (THF) were
charged to a 300 ml autoclave. The autoclave was heated to 120° C.
and a hydrogen pressure of 100 bar was applied. In the course of 120
minutes, a mixture of 16 g of ethylenediaminediacetonitrile (EDDN), 0.5 g
of ethylenediaminomonoacetonitrile (EDMN), 1.3 g of
biscyanomethylimidadzolidine (BCMI) and 100 g of THF was fed to the
autoclave. The reaction mixture was stirred for another 60 minutes at
120° C. and a hydrogen pressure of 100 bar.

[0160] The reaction mixture was narrowed in under a water jet vacuum and
the remaining residue was fractionated at 20 mbar. The fraction taken at
a column head temperature of 150° C. had following composition:
96.5% by weight of linear TETA, 3.1% by weight of Me-TETA and 0.4% by
weight of other organic components.

Example 5

[0161] 100 g of Epilox° A18-00 epoxy resin (Epilox® A 18-00 is
a low viscosity and solventless bisphenol A epoxy resin produced by
LEUNA-Harze GmbH) were mixed with 14 g of an amine curing agent
composition consisting of the amine composition obtained in a) example 1,
b) example 4 or c) a commercial TETA, mixture obtained from Huntsman
containing about 69% by weight linear triethylenetetramine, about 6% by
weight TAEA, about 15% by weight DAEPIP, and about 10% by weight PEEDA.

a) Initial viscosity:

[0162] The mixture of Epilox and the TETA composition was heated to
23° C. and poured into a cardboard beaker in order to measure the
initial viscosity of the mixture. Following val-ues were determined:

a) 2625 mPas for the TETA composition according to example 1; b) 2485
mPas for the TETA composition according to example 3; c) 2903 mPas for
the commercial TETA composition. b) Viscosity increase at 23° C.:

[0163] The development of the viscosity of the initial mixture obtained
according to example 5a) was followed. The time at which the maximum
value for the viscosity was obtained was:

a) 61 minutes for the TETA composition according to example 1; b) 63
minutes for the TETA composition according to example 3; c) 57 minutes
for the commercial TETA composition.

[0164] The linear TETA compositions according to the present invention (a)
and b)) possess a lower initial viscosity than the commercial TETA
compositions. This is advantageous for the filling or construction of
large moldings or construction parts. The time until the maximum
viscosity is reached is proportional to the latency time of the system. A
longer latency is are technically advantageous from a processing
standpoint and offer additional safety, since the autocatalytic curing
reaction does not begin until later.

c) Determination of the onset temperature of the crosslinking reaction by
DSC (differential scanning calorimetry)

[0165] The onset temperature of the crosslinking reaction was as follows:

a) 63° C. for the TETA composition according to example 1; b)
64° C. for the TETA composition according to example 3; c)
61° C. for the commercial TETA composition.

[0166] As stated above, the higher onset temperature of the crosslinking
reaction are technically advantageous from a processing standpoint and
offer additional safety.

d) Determination of the gel point by rheological study

[0167] The activity of resin systems was determined by monitoring the
progress of reaction using a rheometer. This involves plotting a variable
known as the storage modulus against a variable known as the loss
modulus. The point at which the two curves inter-sect is referred to as
the gel point. The corresponding reaction time is known as the gel time,
and constitutes a measure of the reactivity of the epoxy resin system.

[0168] Following gel times were measured:

a) 8.6 minutes for the TETA composition according to example 1; b) 8.3
minutes for the TETA composition according to example 3; c) 9.3 minutes
for the commercial TETA composition.

[0169] The cure time (gel time) of the epoxy resin using the linear TETA
compositions according to the present invention is shortened by
approximately 8 to 10% over the comparative example through the use of
pure linear TETA. This is accompanied by a shortening in the cycle times,
with beneficial effects for investment costs in the case, for example, of
high-volume manufacture of moldings, such as of small carbon fibre
reinforced plastic (CRP) components in the automotive sector.

e) DSC is used to determine the glass transition temperature of the cured
epoxy resin. Cured epoxy resins possess good mechanical properties when
the service temperature is <the glass transition temperature. Above
the glass transition temperature there is a dramatic deterioration in the
mechanical properties of the epoxy resins.

[0170] The glass transition temperatures were found to be:

a) 149° C. for the TETA composition according to example 1; b)
147° C. for the TETA composition according to example 3; c)
124° C. for the commercial TETA composition.

[0171] The glass transition temperature of the epoxy resin cured with the
amine curing agent composition comprising the amine composition according
to the present invention was (a) and b)) approximately more than
20° C. higher than that of the comparative resin. Accordingly the
resin of the inventive example can be used at significantly higher
temperatures.

Patent applications by Achim Kaffee, Lorsch DE

Patent applications by Boris Buschhaus, Mannheim DE

Patent applications by Dominic Suter, Ludwigshafen DE

Patent applications by Gunther Van Cauwenberge, Lokeren BE

Patent applications by Hendrik Heising, Limburgerhof DE

Patent applications by Johann-Peter Melder, Bohl-Lggelheim DE

Patent applications by Kevin Huyghe, Mannheim DE

Patent applications by Kirsten Dahmen, Freinsheim DE

Patent applications by Manfred Kinscherff, Romerberg DE

Patent applications by BASF SE

Patent applications in class Process of forming a composition containing a nonreactive material (NRM) and a polymer containing more than one 1,2-epoxy group, or a preformed polymer derived from or admixed with a reactant containing more than one 1,2-epoxy group, or with a polymer derived from an epihalohydrin and a polyhydric phenol or polyol; or composition or product thereof

Patent applications in all subclasses Process of forming a composition containing a nonreactive material (NRM) and a polymer containing more than one 1,2-epoxy group, or a preformed polymer derived from or admixed with a reactant containing more than one 1,2-epoxy group, or with a polymer derived from an epihalohydrin and a polyhydric phenol or polyol; or composition or product thereof